ITS/AliITStrackMI.cxx

   1 /**************************************************************************
   2  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3  *                                                                        *
   4  * Author: The ALICE Off-line Project.                                    *
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  11  * appear in the supporting documentation. The authors make no claims     *
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  13  * provided "as is" without express or implied warranty.                  *
  14  **************************************************************************/
  15
  16 //-------------------------------------------------------------------------
  17 //                Implementation of the ITS track class
  18 //
  19 //          Origin: Marian Ivanov, CERN, Marian.Ivanov@cern.ch
  20 //     dEdx analysis by: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
  21 //-------------------------------------------------------------------------
  22
  23 #include <TMatrixD.h>
  24
  25 #include <TMath.h>
  26
  27 #include "AliCluster.h"
  28 #include "AliESDtrack.h"
  29 #include "AliITSgeomTGeo.h"
  30 #include "AliITStrackMI.h"
  31
  32 ClassImp(AliITStrackMI)
  33
  34 const Int_t kWARN=5;
  35
  36 //____________________________________________________________________________
  37 AliITStrackMI::AliITStrackMI():AliITStrackV2(),
  38 fNUsed(0),
  39 fNSkipped(0),
  40 fNDeadZone(0),
  41 fDeadZoneProbability(0),
  42 fReconstructed(kFALSE),
  43 fExpQ(40),
  44 fChi22(0),
  45 fdEdxMismatch(0),
  46 fConstrain(kFALSE),
  47 fGoldV0(kFALSE)
  48 {
  49   //constructor
  50     for(Int_t i=0; i<AliITSgeomTGeo::GetNLayers(); i++) fClIndex[i]=-1;
  51     for(Int_t i=0; i<6; i++) { fNy[i]=0; fNz[i]=0; fNormQ[i]=0; fNormChi2[i]=1000;}
  52     for(Int_t i=0; i<12; i++) {fDy[i]=0; fDz[i]=0; fSigmaY[i]=0; fSigmaZ[i]=0; fChi2MIP[i]=0;}
  53     fD[0]=0; fD[1]=0;
  54 }
  55
  56 //____________________________________________________________________________
  57 AliITStrackMI::AliITStrackMI(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
  58 AliITStrackV2(t,c),
  59 fNUsed(0),
  60 fNSkipped(0),
  61 fNDeadZone(0),
  62 fDeadZoneProbability(0),
  63 fReconstructed(kFALSE),
  64 fExpQ(40),
  65 fChi22(0),
  66 fdEdxMismatch(0),
  67 fConstrain(kFALSE),
  68 fGoldV0(kFALSE) {
  69   //------------------------------------------------------------------
  70   // Conversion ESD track -> ITS track.
  71   // If c==kTRUE, create the ITS track out of the constrained params.
  72   //------------------------------------------------------------------
  73   for(Int_t i=0; i<6; i++) {fClIndex[i]=-1; fNy[i]=0; fNz[i]=0; fNormQ[i]=0; fNormChi2[i]=1000;}
  74   for(Int_t i=0; i<12; i++) {fDy[i]=0; fDz[i]=0; fSigmaY[i]=0; fSigmaZ[i]=0;fChi2MIP[i]=0;}
  75   fD[0]=0; fD[1]=0;
  76   //if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
  77
  78 }
  79
  80 void AliITStrackMI::UpdateESDtrack(ULong_t flags) {
  81   fESDtrack->UpdateTrackParams(this,flags);
  82   //if (flags == AliESDtrack::kITSin) fESDtrack->SetITSChi2MIP(fChi2MIP);
  83 }
  84
  85 //____________________________________________________________________________
  86 AliITStrackMI::AliITStrackMI(const AliITStrackMI& t) : AliITStrackV2(t),
  87 fNUsed(t.fNUsed),
  88 fNSkipped(t.fNSkipped),
  89 fNDeadZone(t.fNDeadZone),
  90 fDeadZoneProbability(t.fDeadZoneProbability),
  91 fReconstructed(t.fReconstructed),
  92 fExpQ(t.fExpQ),
  93 fChi22(t.fChi22),
  94 fdEdxMismatch(t.fdEdxMismatch),
  95 fConstrain(t.fConstrain),
  96 fGoldV0(t.fGoldV0) {
  97   //------------------------------------------------------------------
  98   //Copy constructor
  99   //------------------------------------------------------------------
 100   fLab = t.fLab;
 101   fFakeRatio = t.fFakeRatio;
 102
 103   fD[0]=t.fD[0]; fD[1]=t.fD[1];
 104   fDnorm[0] = t.fDnorm[0]; fDnorm[1]=t.fDnorm[1];
 105   for(Int_t i=0; i<6; i++) {
 106     fClIndex[i]= t.fClIndex[i]; fNy[i]=t.fNy[i]; fNz[i]=t.fNz[i]; fNormQ[i]=t.fNormQ[i]; fNormChi2[i] = t.fNormChi2[i];
 107   }
 108   for(Int_t i=0; i<12; i++) {fDy[i]=t.fDy[i]; fDz[i]=t.fDz[i];
 109     fSigmaY[i]=t.fSigmaY[i]; fSigmaZ[i]=t.fSigmaZ[i];fChi2MIP[i]=t.fChi2MIP[i];}
 110   //memcpy(fDy,t.fDy,6*sizeof(Float_t));
 111   //memcpy(fDz,t.fDz,6*sizeof(Float_t));
 112   //memcpy(fSigmaY,t.fSigmaY,6*sizeof(Float_t));
 113   //memcpy(fSigmaZ,t.fSigmaZ,6*sizeof(Float_t));
 114   //memcpy(fChi2MIP,t.fChi2MIP,12*sizeof(Float_t));
 115 }
 116
 117 //_____________________________________________________________________________
 118 Int_t AliITStrackMI::Compare(const TObject *o) const {
 119   //-----------------------------------------------------------------
 120   // This function compares tracks according to the their curvature
 121   //-----------------------------------------------------------------
 122   AliITStrackMI *t=(AliITStrackMI*)o;
 123   //Double_t co=TMath::Abs(t->Get1Pt());
 124   //Double_t c =TMath::Abs(Get1Pt());
 125   Double_t co=t->GetSigmaY2()*t->GetSigmaZ2()*(0.5+TMath::Sqrt(0.5*t->fD[0]*t->fD[0]+t->fD[1]*t->fD[1]));
 126   Double_t c =GetSigmaY2()*GetSigmaZ2()*(0.5+TMath::Sqrt(0.5*fD[0]*fD[0]+fD[1]*fD[1]));
 127   if (c>co) return 1;
 128   else if (c<co) return -1;
 129   return 0;
 130 }
 131
 132
 133 Double_t AliITStrackMI::GetPredictedChi2MI(Double_t cy, Double_t cz, Double_t cerry, Double_t cerrz) const
 134 {
 135   //-----------------------------------------------------------------
 136   // This function calculates a predicted chi2 increment.
 137   //-----------------------------------------------------------------
 138   Double_t p[2]={cy, cz};
 139   Double_t cov[3]={cerry*cerry, 0., cerrz*cerrz};
 140   return AliExternalTrackParam::GetPredictedChi2(p,cov);
 141 }
 142
 143 //____________________________________________________________________________
 144 Int_t AliITStrackMI::CorrectForMaterial(Double_t d, Double_t x0) {
 145   //------------------------------------------------------------------
 146   //This function corrects the track parameters for crossed material
 147   //------------------------------------------------------------------
 148   //d=x0=0.;
 149
 150   Double_t p2=(1.+ GetTgl()*GetTgl())/(GetSigned1Pt()*GetSigned1Pt());
 151   Double_t et   = p2 + GetMass()*GetMass();
 152   Double_t beta2=p2/et;
 153   et = sqrt(et);
 154   d*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
 155
 156   //Multiple scattering******************
 157   if (d!=0) {
 158      Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
 159      //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
 160      Cov(5) += theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
 161      Cov(9) += theta2*(1. + GetTgl()*GetTgl())*(1. + GetTgl()*GetTgl());
 162      Cov(13)+= theta2*GetTgl()*GetSigned1Pt()*(1. + GetTgl()*GetTgl());
 163      Cov(14)+= theta2*GetTgl()*GetSigned1Pt()*GetTgl()*GetSigned1Pt();
 164   }
 165
 166   //Energy losses************************
 167   if (x0!=0.) {
 168      d*=x0;
 169      //     Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
 170      //Double_t dE=0;
 171      Double_t dE = 0.265*0.153e-3*(39.2-55.6*beta2+28.7*beta2*beta2+27.41/beta2)*d;
 172      //if (beta2/(1-beta2)>3.5*3.5){
 173      //  dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
 174      //}
 175      //else{
 176      //  dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
 177      //  dE+=0.06e-3/(beta2*beta2)*d;
 178      //}
 179
 180      Par(4)*=(1.- et/p2*dE);
 181      Double_t delta44 = (dE*GetSigned1Pt()*et/p2);
 182      delta44*=delta44;
 183      Cov(14)+= delta44/400.;
 184   }
 185
 186   if (!Invariant()) return 0;
 187
 188   return 1;
 189 }
 190
 191 //____________________________________________________________________________
 192 Bool_t AliITStrackMI::UpdateMI(Double_t cy, Double_t cz, Double_t cerry, Double_t cerrz, Double_t chi2, Int_t index) {
 193   //------------------------------------------------------------------
 194   //This function updates track parameters
 195   //------------------------------------------------------------------
 196   Double_t dy=cy - GetY(), dz=cz - GetZ();
 197   Int_t layer = (index & 0xf0000000) >> 28;
 198   fDy[layer] = dy;
 199   fDz[layer] = dz;
 200   fSigmaY[layer] = TMath::Sqrt(cerry*cerry+GetSigmaY2());
 201   fSigmaZ[layer] = TMath::Sqrt(cerrz*cerrz+GetSigmaZ2());
 202
 203   Double_t p[2]={cy, cz};
 204   Double_t cov[3]={cerry*cerry, 0., cerrz*cerrz};
 205   if (!AliExternalTrackParam::Update(p,cov)) return kFALSE;
 206
 207   if (!Invariant()) {
 208      AliWarning("Wrong invariant !");
 209      return kFALSE;
 210   }
 211
 212   if (chi2<0) return 1;
 213   Int_t n=GetNumberOfClusters();
 214   fIndex[n]=index;
 215   SetNumberOfClusters(n+1);
 216   SetChi2(GetChi2()+chi2);
 217
 218   return kTRUE;
 219 }
 220
 221 Int_t AliITStrackMI::GetProlongationFast(Double_t alp, Double_t xk,Double_t &y, Double_t &z)
 222 {
 223   //-----------------------------------------------------------------------------
 224   //get fast prolongation
 225   //-----------------------------------------------------------------------------
 226   Double_t ca=TMath::Cos(alp-GetAlpha()), sa=TMath::Sin(alp-GetAlpha());
 227   Double_t cf=TMath::Sqrt(1.- GetSnp()*GetSnp());
 228   // **** rotation **********************
 229   y= -GetX()*sa + GetY()*ca;
 230   // **** translation ******************
 231   Double_t dx = xk- GetX()*ca - GetY()*sa;
 232   Double_t f1=GetSnp()*ca - cf*sa, f2=f1 + GetC()*dx;
 233   if (TMath::Abs(f2) >= 0.9999) {
 234     return 0;
 235   }
 236   Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
 237   y += dx*(f1+f2)/(r1+r2);
 238   z  = GetZ()+dx*(f1+f2)/(f1*r2 + f2*r1)*GetTgl();
 239   return 1;
 240 }
 241
 242
 243 Bool_t AliITStrackMI::IsGoldPrimary()
 244 {
 245   //
 246   // Indicates gold pimary track
 247   //
 248   Bool_t isGold=kTRUE;
 249   if (!fConstrain) return kFALSE;                //
 250   if (fNDeadZone+fNDeadZone<5.5) isGold =  kFALSE; // short track
 251   //
 252   if (fChi2/Float_t(fN)>2.){
 253     if (fChi2MIP[0]+fNUsed>3.5) isGold = kFALSE;
 254   }
 255   if (fChi2MIP[2]>4.5) isGold = kFALSE;         //back propagation chi2
 256   //
 257   if (fDnorm[0]>0&&fDnorm[1]>0){
 258     const Float_t distcut2 =2.5*2.5;  //normalize distance  cut
 259     Float_t dist2 = fD[0]*fD[0]/(fDnorm[0]*fDnorm[0])+fD[1]*fD[1]/(fDnorm[1]*fDnorm[1]);  //normalize distance to the vertex (pools)
 260     if (dist2>distcut2) isGold = kFALSE;
 261   }
 262   return isGold;
 263 }